#!/usr/bin/env bash

fbdev=/dev/fb0 ;   width=1280 ; bpp=4
color="\x00\x00\xFF\x00" #red colored

function pixel()
{  xx=$1 ; yy=$2
   printf "$color" | dd bs=$bpp seek=$(($yy * $width + $xx)) \
                        of=$fbdev 
                        # &>/dev/null
}
x=0 ; y=0 ; clear
for i in {1..500}; do
   pixel $((x++)) $((y++))
done
